Ad-hoc networks are groups of interconnected devices, such as computers or transceivers, in which the topology and/or connectivity of the network may change at any time. Ad-hoc networks are advantageously used in circumstances where a plurality of devices desire or are required to communicate with each other.
In a wireless network, bandwidth is driven by the available RF spectrum, which is currently a scarce commodity. In this environment the most significant challenge associated with a broad-band wireless network is efficiently using the limited bandwidth provided by the network. This problem is made worse by the needs of a distributed network, which requires most or all of the nodes in the network to broadcast and/or multicast information to thereby pass the information through the network. Such broadcasting can take up a great deal of system bandwidth since a message may need to be repeated throughout the system. In a wired internet protocol (IP) based network, reducing the system load of broadcast services is resolved by isolating the broadcast area to a defined region of the network. In a mobile ad-hoc network, however, such isolation is not possible because the IP addresses do not represent a defined group of people within a fixed geographic region or location.
One type of mobile ad-hoc network in which broadcast communications may be overtaxed comprises a plurality of military resources or nodes such as tanks, infantry, unmanned aerial vehicles (UAVs), autonomous sensors, helicopters, and fixed-wing aircraft. A request for helicopter assistance by an infantry unit, for example, would be transmitted to non-helicopter nodes throughout the network. Furthermore, because many of the military nodes are mobile, the request directed to helicopters would likely be sent to helicopters beyond a range that would be useful to assist the infantry unit. In either case, broadcast bandwidth is needlessly wasted by transmitting messages to nodes in the network that cannot assist the requesting node. What is therefore needed is a communications protocol that conserves communications resources while ensuring messages are transmitted to the desired nodes in a mobile ad-hoc network.
It is therefore an object of the invention to provide a communications protocol that conserves communications resources such as broadcast bandwidth.
It is another object of the invention to transmit messages in an ad-hoc mobile network such that nodes of a specific type receive the message.
It is still another object of the invention to transmit messages in an ad-hoc mobile network such that nodes of a specific type and distance from a transmitting node receive the message.
A feature of the invention is a method of transmitting a message directed to a specific type of network node within a predetermined distance from the transmitting node.
An advantage of the invention is the conserving of communications resources by limiting the actual distance a message is to be transmitted through the network.